While concrete or cement is a very popular material for use in floors and construction materials because of its strength, durability and low costs, if the concrete or cement is left unfinished, the concrete floor will inherently produce dust by the constant scuffing it undergoes whether by foot traffic or wheeled traffic and be susceptible to staining due to porosity.
One is thus faced with a dilemma of cleaning a concrete floor with its no gloss utilitarian appearance and with the disadvantage of the inevitable dust that emanates from an unfinished concrete floor or spending considerable money for a protective and decorative covering surface. Vast improvements in coatings for concrete floors have taken place in the recent past and one may also desire to remove an older worn or failed coating and replace it with one of the newer type coatings. Part of the expense to obtain a decorative and protective covering is due to the preparation of the concrete floor to accept the new covering surface. The preparation often includes aggressive sanding to rough up the concrete surface and to remove any previously applied top coating, oil, or grease stains to assure proper adhesion of the new covering. Aggressive sanding of the concrete surface with conventional sand paper on sanding machines is a time consuming effort requiring frequent replacement of the sand paper as the sand particles become worn.
Attempts for more aggressive sanding and grinding pads have incorporated hardened particles such as diamonds or silicon carbide. While these pads performed well when new, it has been found that only a small percentage of the particles actually touch the surface at a give time. The cutting edges of these few engaging particles become rounded out through wear and the sanding performance substantially diminishes. In the trade, this is sometimes referred to as a ball bearing effect because the few now rounded diamond particles glide over the surface and no longer effectively cut into the surface.
Other problems are known that also prevent or limit the application of hardened particles. The present application of an abrasive bristle made from today's known higher temperature plastic materials when combined with the aforementioned hard abrasive materials generate much heat when used on a high speed power sander. The generated heat is sufficient to melt the plastic material and fuses the abrasive bristles together rendering the bristle pad useless.
The high heat and slow grinding rates pose particular problems for preparation of concrete surfaces that have mastic or older plastic and paints previously coated thereon. The heat melts the old coating materials as it is removed and the coating then adheres to and gums up the bristles which then quickly lose most of their sanding and grinding effectiveness.
Previous attempts to produce metal bristles also encountered problems. Attempts have been made to provide hard particles such as silicon carbide or diamond secured onto a bristle strip, blade or plate. The hard particles may be diamond particles brazed onto spring steel or other metal substrate. If the metal substrate is fully brazed with particles, the substrate becomes too brittle and breaks off during high speed application. Even spring steel loses its resilient spring nature after it undergoes brazing. Attempts to limit the diamond particles only to the extreme ends or tips of the bristles to maintain the flexibility of the metal dramatically shorten the workable life of the bristle.
What is needed is an abrasive device for concrete sanding that has an improved performance profile by incorporating hardened particles only along a front face of a distal section of a substrate layer and which expose new particle edges as the substrate layer wears down. What is also needed is a flexible metal abrasive element with hardened particles secured thereon with the brazed section only on a front facing distal section of a substrate layer. What is also needed is a metal substrate layer with particles brazed thereon and further reinforced and supported by a resilient backing element to maintain sufficient flexibility and support of the metal substrate layer.
What is also needed is a durable abrasion element assembly for mounting to a cleaning or sanding machine that is suitable for preparing cement floors for coating. What is also needed is an expedient method to prepare a polished concrete floor to cut away plastic, mastic and the other heat sensitive materials by an aggressive cutting which forms enough concrete dust to coat the removed waste product before it can stick or adhere to the surfaces of the abrasion element assembly. What is also needed is an abrasion element assembly that has abrasive particles securely affixed to a substrate layer that is reinforced and supported by a resilient backing layer. What is also needed is an efficient sanding element that can be used with decreased horsepower most commonly available on consumer oriented sanding and cleaning machines.